There have been developed various methods for producing (meth)acrylic resin composition for optical component. For example, Patent Document 1 discloses a method comprising continuously feeding a recycled liquid containing monomer component mainly comprising unreacted methyl methacrylate recovered after polymerization as well as a monomer component mainly comprising fresh methyl methacrylate to a distillation column, continuously feeding the resulting distilled monomer components into a polymerization reaction tank for bulk polymerization, subsequently devolatizing the resulting liquid containing a polymerization product to recover the polymerization product and simultaneously recovering an unreacted monomer for use as a recycled liquid, and feeding a solvent having a boiling point higher than boiling points of the monomers to a bottom of the distillation column and simultaneously discharging a bottom liquid from the bottom in the same amount as that of the solvent being fed.
Patent Document 2 discloses a method comprising continuously feeding a monomer component mainly comprising methyl methacrylate to a polymerization reaction tank for bulk polymerization, subsequently devolatizing the resulting liquid containing a polymerization product to recover the polymerization product and simultaneously conducting distillation to recover an unreacted monomer for recycling, and removing an acidic substance present in the system by using a basic anion exchange resin.
Patent Document 3 discloses a method comprising continuously feeding a monomer component mainly comprising methyl methacrylate to a polymerization reaction tank for bulk polymerization, subsequently conducting devolatizing treatment of the resulting liquid containing a polymerization product to separate an unreacted monomer, introducing the separated an unreacted monomer to a distillation column, and conducting distillation under reduced pressure so that the content of methyl methacrylate dimer reaches 0.1 to 1.0% by mass whereby the monomer is recovered.
The reaction product solution obtained after bulk polymerization contains an unreacted polymerizable monomer component as well as a relatively great amount of an unreached chain transfer agent. The unreacted polymerizable monomer component can be recovered and reused to some extent in the methods described in Patent Documents 1 to 3, whereas the rate of recovery of the unreacted chain transfer agent is low and therefore most of the unreacted chain transfer agent is discarded. Patent Document 4 or 5 suggests a method for recovering a chain transfer agent, but this method requires use of equipment for treating hydrazines that are added to the system.